The subject invention provides for a new and improved boring cutter having a unique insert seat and wedge assembly which permits the outer diameter of the boring cutter to be readily adjusted. In addition, the desired overhang between the indexable insert and the wedge is maintained thereby reducing the likelihood of insert breakdown.
In the prior art, boring cutters are provided for machining metal parts made of cast iron, aluminum or steel. The prior art boring cutters are generally circular in configuration and are adapted to be rotated around a central axis. The cutters are provided with a plurality of insert pockets disposed around the periphery thereof, which are adapted to receive indexable cutting inserts, each insert having a plurality of sharpened cutting edges. In order to accurately locate and maintain the indexable cutting inserts within each pocket, various wedge assemblies have been employed which are mounted in the cutter pockets along with the inserts. The prior art wedge assemblies are removable since the exposed or active cutting edges of the inserts will become worn after a period of use such that the inserts must be rotated to expose a fresh sharpened cutting edge. Accordingly, the wedge assemblies are removable to enable the inserts to be indexed.
Heretofore, when utilizing random industry inserts, numerous difficulties arise when attempts are made to adjust the outer diameter of a milling cutter. The outer diameter is defined as the diameter of an imaginary circle which is coincident with the outermost end points or cutting edges of the insert. To enable the boring cutter to machine a part within the required tolerances, it is necessary that each of the cutting edges of the insert be accurately positioned to conform to the desired outer diameter. Thus, the radial position of the insert, relative to the central axis of the boring cutter must be accurately set and maintained. In addition, it is often desirable to change the outside diameter of a boring cutter to enable the cutter to act as a finisher, semi-finisher or rougher.
Heretofore, the desired outer diameter of the boring cutter was achieved by adding shims between the edge faces of the insert and the pocket of the boring cutter. More particularly, additional wedges or shims are placed between the insert and the pocket of the cutter to force the insert radially outwardly. To complete the fine adjustments necessary to produce an accurate and circular outer diameter, the boring cutter with inserts and shims mounted therein is spun ground until the proper diameter is achieved. Spin grinding is accomplished by placing the cutter on a mandrel between centers, and grinding the inserts until an accurate, circular outer diameter is obtained. The spin grinding of the boring cutter, to obtain the proper outer diameter, is both a difficult and time consuming procedure. Further, the use of shims, which are placed between the insert and the pocket of the boring cutter, increases the likelihood of insert breakdown. More specifically, as additional shims are added and the radial position of the insert is moved progressively outward, an increasingly larger portion of the insert is left unsupported. For example, in many prior art assemblies, a steel wedge is inserted between the trailing wall of the insert pocket and the carbide insert. In the latter arrangement, the amount which the carbide insert overhangs beyond the edge of the steel wedge is critical to the support of the cutting edge of the insert. As the insert is moved radially outwardly, a larger portion of the insert overhangs the wedge, and is thereby left unsupported which increases the likelihood of the fracturing of the insert. Thus, as noted above, as shims are used to control the outer diameter of the cutter, the overhang of the insert is increased which can lead to the fracture of the cutting edge of the insert.
Accordingly, it is an object of the subject invention to provide a new and improved adjustable insert seat and wedge assembly wherein the desired outer diameter of the boring cutter can be readily achieved by adjusting the radial position of the insert.
It is a further object of the subject invention to provide an adjustable insert seat and wedge assembly wherein the outer diameter of the boring cutter may be readily adjusted while maintaining the amount of overhang between the indexable insert and wedge thereby minimizing the likelihood of the fracturing of the cutting edge of the insert.
It is another object of the subject invention to provide an insert seat and wedge assembly which may be used to accurately fix the position of an indexable insert at the desired axial and radial rake angles.
It is still a further object of the subject invention to provide an adjustable insert seat and wedge assembly wherein the outer diameter of the boring cutter can be readily changed to accommodate various industry inserts such as utility inserts and press and treat inserts, and finishing inserts.
It is still another object of the subject invention to provide an insert seat and wedge assembly which enables a conventional fixed pocket boring cutter to be adapted for use as a rougher, finisher, or semi-finisher.